Electric fuse



' July 21,1936. o. H. JUNG ET AL ELECTRIC FUSE Filed April 16, 1934 737/1 5 /lffFfL F//vefR Patented July 21, 1936 ELECTRIC FUSE Oscar H. Jung and Paul E. Heffelfinger, Milwaukee, Wis., assignors to Trico Fuse Mfg. Co.,

Milwaukee, Wis.

LApplication April 16, 1934, 'Serial No. '720,771 3 Claims. (Omoo-131) This invention pertains to electric fuses, and more particularly to fuses of the renewable type. In the present renewable fuses of the ferrule type, in which the end caps serve as terminals, considerable difficulty is encountered in obtaining the desired Contact between the at turned over ends of the renewable link and the terminal caps, and also in preventing loosening of the caps during use or handling of the fuse, with the result that the necessary contact becomes broken.

The present invention has primarily for its object to overcome the foregoing objections by the provision of a fuse of the character set forth, provided with simple, inexpensive, and efficient means for insuring intimate binding contact between the ends of the renewable fuse and the cap terminals, said means further serving to bind the caps upon their threaded connections with the fuse casing, thus preventing loosening of the caps 20 through subsequent handling or use.

Incidental to the foregoing, a more specic object of the invention resides in providing the terminal caps with independent threaded plugs accessible from the outside of the caps for binding engagement with the ends of the renewable link.

With the above and other objects in view, which will appear as the description proceeds, the invention resides in the novel construction, combination and arrangement of parts, substantially as 30 hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the herein disclosed invention may be made as come within the scope of the claims. 30 In the accompanying drawing is illustrated one complete example of the physical embodiment of the present invention constructed according to the best mode so far devised for the practical application of the principles thereof.

In the drawingz- Figure 1 is a longtudinal section through a fuse constructed in accordance with one form of the present invention.

45 Figure 2 is a fragmentary section taken on the line 2--2 of Figure 1, and

Figure 3 is a transverse section taken on the line 3 3 of Figure 1. K

With particular reference to the drawing, the numeral l indicates a fibrous tubular casing having slotted closures 2 threaded exteriorly upon its ends. A renewable flat link 3 is positioned within the casing I and has its ends 3 projected through the slotted closures and bent over upon 55 the same, as best shown in Figure 2. The outer periphery of the closures 2 are threadedfor reception of the terminal caps 4. v

Conventional structures of the foregoing character depend entirely upon turning the terminal caps 4 down upon the end closures 2 for secur- 5 ing the necessary contact between the renewable link 3 and the terminal caps 4. However, in such structures considerable difficulty has been encountered in turning the caps 4 down upon the end closures with suicient force to obtain the del0 sired contact, even though various tools are employed in the operation. Furthermore, the terminal caps 4 have a tendency to become loosened in subsequent handling and use.

The present invention overcomes the foregoing objections by the provision of plugs 5 threaded into the ends of the terminals 4, the plugs being accessible from the exterior of the caps, which permits them to be run down upon the ends of the renewable link by means of a screw-driver, or other suitable tool. Obviously the plugs 5, in cooperation with the slotted closures 2, eifect a binding engagement between the ends of the link 3 and the terminals 4, which insures the necessary contact between the same.

In the preferred form of the invention the threads of the plugs 5 are somewhat finer than those between the closures 2 and the terminals 4, thus enabling the plugs 5 to be turned down with comparatively little effort, and at the same time creating a binding engagement between the plugs and the ends of the renewable link, that also binds the threads of the terminals 4 upon those of the end closures 2, which serves effectively as a locking means to prevent the terminals 4 from be-'35 coming loosened subsequent to use or handling. Preferably, in order to prevent loosening or misplacement of the plugs 5, and to enable the same to be turned down upon the ends of the fuse of the renewable link, as the terminals 4 are thread- 40 ed upon the end closures, the plugs are provided with ilanges 5', which engage the inner faces of the ends of the terminals.

Obviously, from the foregoing explanation, considered in connection with the accompanying drawing, it will be readily seen that an extremely simple, inexpensive, and effective structure has been provided for securing and maintaining intimate binding contact between the renewable link and end terminals in fuses of the type to which the invention applies. Attention is also directed to the fact that the specic structure of the end closures and terminals may be varied without departing from the present invention, the salient feature of which resides in the provision of independently operable means carried by the end terminals for securing and obtaining the desired contact between the renewable link and the terminals.

We claim:-

1. In a renewable fuse including a tubular casing having a continuous wall, detachable closures for the ends of the casing provided with openings, a at renewable link having its ends projecting through and bent over upon said closures, removable terminal caps in threaded connection with the ends of said casing; threaded plugs centrally carried by said terminal caps for binding engagement with the turned over ends of the renewable link, the threads of said plugs being of less pitch than those of the terminal caps.

2. In a renewable fuse including a tubular casing having a continuous wall, closures detachably secured to the ends of the casing provided with openings, a flat renewable link having its ends projecting through and bent over upon said closures, and removable terminal caps threaded upon said closures; and threaded plugs centrally carried by said terminal caps for binding engagement with the ends of said renewable link, the threads of said plugs being of less pitch than those of said terminal caps.

3. In a renewable fuse including a, tubular cas-V ing having a continuous wall, closures detachably secured to the ends of the casing provided with end slots, said closures including continuous annular walls threaded on said casing, a flat renewable link having its ends projecting through and bent over upon said closures, and removable terminal caps threaded upon said slotted closures; threaded plugs centrally carried by said terminal caps for binding engagement with the ends of said renewable link, the threads of said plugs being of less pitch than those of said terminal caps, said plugs being accessible from the exterior of said caps.

OSCAR H. JUNG. PAUL E. HEFFELFINGER. 

